The present invention relates to a vehicle controller capable of changing control software to a control algorithm newly developed to improve the performance early and by a relatively inexpensive apparatus in a market after selling a vehicle.
An electric-power-steering controller is described below as one of the conventional vehicle controllers. FIG. 3 is a circuit diagram of the conventional power-steering controller disclosed in Japanese Patent Application No. 5-64268 in which a part of the controller is shown by a block diagram. In FIG. 3, a motor 40 for outputting an auxiliary torque to a vehicle steering wheel (not illustrated) is driven by a motor current IM supplied from a battery 41. The ripple component of the motor current IM is absorbed by a capacitor 42 having a large capacity (1,000 xcexcF to 3,600 xcexcF) and detected by a shunt resistor 43. Moreover, directions and values of the motor current IM are switched in accordance with the operation of a bridge circuit 44 having a plurality of semiconductor switching devices (e.g. FETs) Q1 to Q4 in accordance with the magnitude and direction of the auxiliary torque.
One end of the capacitor 42 is connected to the ground by a conductive wire L1. The semiconductor switching devices Q1 to Q4 are bridge-connected by wiring patterns P1 and P2 to constitute a bridge circuit 44. Moreover, the wiring patterns P1 and P2 connect the bridge circuit 44 to the shunt resistor 43. The output terminal of the bridge circuit 44 is constituted with a wiring pattern P3.
The motor 40 and battery 41 are connected to the bridge circuit 44 through the wiring pattern P3 by a connector 45 having a plurality of lead terminals. The motor 40 and battery 41 are connected to the connector 45 by an external wiring L2. The motor current IM is supplied or cut off by a normally-open relay 46 according to necessity. The relay 46, capacitor 42, and shunt resistor 43 are connected each other by a wiring pattern P4. The connector 45 is connected to the ground by a wiring pattern P5. The wiring pattern P3 serving as the output terminal of the bridge circuit 44 is connected to the connector 45.
The motor 40 is driven by a driving circuit 47 through the bridge circuit 44. Moreover, the driving circuit 47 drives the relay 46. The driving circuit 47 is connected to the exciting coil of the relay 46 by a conductive wire L3. Moreover, the driving circuit 47 is connected to the bridge circuit 44 by a conductive wire L4. The motor current IM is detected by a motor current detection means 48 in accordance with the voltage appearing at the both ends of the shunt resistor 43. The driving circuit 47 and motor current detection means 48 constitute the peripheral circuit element of a microcomputer 55 to be mentioned later.
The steering torque T of a steering wheel is detected by a torque sensor 50 and the speed V of a vehicle is detected by a speed sensor 51. The microcomputer 55 (ECU) computes an auxiliary torque in accordance with the steering torque T and vehicle speed V, generates a driving signal corresponding to the auxiliary torque by returning the motor current IM, and outputs a rotational direction command D0 and a current controlled variable I0 for controlling the bridge circuit 44 to the driving circuit 47 as driving signals.
The microcomputer 55 is provided with motor current decision means 56 for generating the rotational direction command D0 for the motor 40 and a motor current command Im corresponding to an auxiliary torque, subtraction means 57 for computing a current deviation xcex94I between the motor current command Im and the motor current IM, and PID operation means 58 for computing correction values of P (proportion) term, I (integration) term, and D (differentiation) term in accordance with the current deviation xcex94I and generating the current controlled variable I0 corresponding to a PWM duty ratio.
Moreover, though not illustrated, the microcomputer 55 includes a publicly-known self-diagnostic function in addition to an AD converter and a PWM timer circuit, always self-diagnoses whether a system normally operates, and cuts off the motor current IM by releasing the relay 46 through the driving circuit 47 when a trouble occurs. The microcomputer 55 is connected to the driving circuit 47 through a conductive wire L5.
Then, operations of a conventional electric-power-steering controller are described below by referring to FIG. 3. The microcomputer 55 captures the steering torque T and vehicle speed V from the torque sensor 50 and speed sensor 51, feedback-inputs the motor current IM from the shunt resistor 43, and generates the rotational direction command D0 of a power steering and the current controlled variable I0 corresponding to an auxiliary torque to output them to the driving circuit 47 through the conductive wire L5.
The driving circuit 47 closes the normally-open relay 46 in accordance with a command through the conductive wire L3 under a normally driving state but it generates a PWM driving signal when the rotational direction command D0 and current controlled variable I0 are input and applies the signal to the semiconductor switching devices Q1 to Q4 of the bridge circuit 44 through the conductive wire L4.
According to the above circuit structure, the motor current IM is supplied from the battery 41 to the motor 40 through the external wiring L2, connector 45, relay 46, wiring pattern P4, shunt resistor 43, wiring pattern P1, bridge circuit 44, wiring pattern P3, connector 45, and external wiring L2. The motor 40 is driven by the motor current IM to output a required mount of auxiliary torque in a required direction.
In this case, the motor current IM is detected through the shunt resistor 43 and motor current detection means 48 and returned to the subtraction means 57 in the microcomputer 55 and thereby, controlled so as to coincide with the motor current command Im. Moreover, though the motor current IM includes ripple components because of the switching operation of the bridge circuit 44 under PWM driving, it is smoothed and controlled by the large-capacity capacitor 42.
A vehicle controller including this type of electric-power-steering controller conventionally uses a microcomputer having a built-in mask ROM storing control software such as control data and control programs.
However, because it is necessary to secure a predetermined mask ROM fabrication period under short-time system development, it is not temporally permitted to re-fabricate a mask ROM due to re-modification of software specification and it is necessary to early fix the software specification. Therefore, this causes the loads of development engineers to increase.
Moreover, also when changing control software for a newly-developed control algorithm in order to improve the performance in a market, it is necessary to secure a predetermined mask ROM fabrication period. However, it is impossible to re-fabricate a mask ROM because of changing the control software for the newly-developed control algorithm and to early change the control software in accordance with the newly-developed control algorithm. Furthermore, to reload the control software in a market, it is necessary to prepare an inexpensive auxiliary storage.
General control software is constituted with the part of discrete corresponding data between an input/output unit connected to a controller and the controller, the part of intrinsic data (e.g. torque-sensor neutral point learning data after final combination of the torque sensor 50 serving as an input/output unit with the controller of a vehicle or trouble history data in the controller mounted on a vehicle in a market after selling the vehicle), and the part of control algorithm.
Thus, the stored intrinsic data content of the intrinsic data storage block (region) in the control software of a storage to be mentioned later corresponds to each input/output unit and the controller one to one. Therefore, to reload the control software in a market, it is necessary to change the intrinsic data storage block (region) to an unerasable block (region).
The present invention is made to solve the above problem and its object is to provide a vehicle controller making it possible to relatively inexpensively, easily, early change control software in a market after selling the vehicle correspondingly to performance improvement.
1. An occasionally-erasable nonvolatile memory built in a vehicle control computer and storing control processing information and auxiliary storage means for setting an unerasable region to the occasionally-erasable nonvolatile memory and updating the control processing information in an erasable region to new control processing information are used.
2. The auxiliary storage means is constituted by adding an information writing function to the occasionally-erasable nonvolatile memory of a troubleshooting unit for reading trouble history information from the memory built in the vehicle control computer.
3. The auxiliary storage means is provided with means for deciding whether the control processing information in the unerasable region of the occasionally-erasable nonvolatile memory is updated.
4. The vehicle control computer is provided with another nonvolatile memory for storing the control processing information in the unerasable region in addition to the occasionally-erasable nonvolatile memory.
5. Storage connection means for setting the occasionally-erasable nonvolatile memory to the erasable mode when the auxiliary storage is connected is used.